Flow measuring device

Abstract

A flow measuring device includes a housing, a support, and a flow measurement element. The housing defines a passage therein and includes a passage narrowing part, which reduces a cross-sectional area of the passage, in a predetermined part of the passage. The support has a platy shape and is disposed along a flow direction of fluid flowing in the passage. The flow measurement element is located inside the passage narrowing part and is disposed on a surface of the support. The flow measurement element detects a flow rate of fluid flowing in the passage. The passage narrowing part has an inner wall surface that gradually reduces a width of the passage from a center side to both end sides of the passage in a height direction of the passage, which is perpendicular to a direction of the width of the passage.

What is claimed is: 
     
       1. A flow measuring device comprising:
 a housing defining a passage therein and including a passage narrowing part, which reduces a cross-sectional area of the passage, in a predetermined part of the passage; 
 a support having a platy shape and disposed along a flow direction of fluid flowing in the passage; and 
 a flow measurement element which is located inside the passage narrowing part and disposed on a surface of the support, the flow measurement element being configured to detect a flow rate of fluid flowing in the passage, wherein the passage narrowing part has an inner wall surface that gradually reduces a width of the passage from a center side to both end sides of the passage in a height direction of the passage, which is perpendicular to a direction of the width of the passage. 
 
     
     
       2. The flow measuring device according to  claim 1 , wherein:
 the passage narrowing part is formed such that a distance between the inner wall surface of the passage narrowing part adjacent to the flow measurement element and the flow measurement element along the direction of the width of the passage is smaller than a distance between a first width narrowest part of the inner wall surface at one of the both end sides of the passage and the flow measurement element along the height direction of the passage, and than a distance between a second width narrowest part of the inner wall surface at the other one of the both end sides of the passage and the flow measurement element along the height direction of the passage; 
 the first width narrowest part has the narrowest width of the passage within a first range between the center side and the one of the both end sides of the passage; and 
 the second width narrowest part has the narrowest width of the passage within a second range between the center side and the other one of the both end sides of the passage. 
 
     
     
       3. The flow measuring device according to  claim 2 , wherein the direction of the width of the passage is a thickness direction of the support having the platy shape. 
     
     
       4. The flow measuring device according to  claim 1 , wherein the height direction of the passage is a direction perpendicular to a thickness direction of the support having the platy shape. 
     
     
       5. The flow measuring device according to  claim 1 , wherein:
 the housing further includes a curved passage part, which defines the passage, on an upstream side or a downstream side of the passage narrowing part in the flow direction of fluid; 
 the curved passage part changes the flow direction of fluid perpendicularly; and 
 the passage narrowing part is formed such that:
 the passage narrowing part includes one inner wall surface and the other inner wall surface, which define the passage and are opposed to each other in the height direction of the passage; 
 the one inner wall surface of the passage narrowing part is formed continuously with a radially outward part of an inner wall surface of the curved passage part; 
 the other inner wall surface of the passage narrowing part is formed continuously with a radially inward part of the inner wall surface of the curved passage part; and 
 a distance from the flow measurement element to the other inner wall surface of the passage narrowing part in the height direction of the passage is larger than a distance from the flow measurement element to the one inner wall surface of the passage narrowing part in the height direction of the passage. 
 
 
     
     
       6. The flow measuring device according to  claim 1 , wherein the passage narrowing part defines only an element disposing part of the passage in which the flow measurement element is disposed. 
     
     
       7. The flow measuring device according to  claim 1 , wherein the passage narrowing part defines a narrowing passage space having a triangular shape in cross-section on the both end sides or one side of the passage in the height direction of the passage. 
     
     
       8. The flow measuring device according to  claim 1 , wherein the passage narrowing part defines a narrowing passage space having a trapezoidal shape in cross-section on the both end sides or one side of the passage in the height direction of the passage. 
     
     
       9. The flow measuring device according to  claim 1 , wherein the passage narrowing part defines a narrowing passage space having a semicircular shape in cross-section on the both end sides or one side of the passage in the height direction of the passage. 
     
     
       10. The flow measuring device according to  claim 1 , wherein the passage narrowing part is formed in a narrowing shape which is capable of aligning a flow of fluid flowing in the passage along a forward direction or a backward direction of the flow of fluid. 
     
     
       11. The flow measuring device according to  claim 1 , wherein the passage narrowing part is formed in a narrowing shape which is capable of aligning a flow of fluid flowing in the passage only along a forward direction of the flow of fluid. 
     
     
       12. The flow measuring device according to  claim 1 , wherein a ridge line of the inner wall surface of the passage narrowing part, which gradually reduces the width of the passage in the flow direction of fluid flowing in the passage, is formed in a curved or linear manner. 
     
     
       13. The flow measuring device according to  claim 1 , wherein:
 the inner wall surface of the passage narrowing part includes a straight line part near the flow measuring element; and 
 the straight line part maintains the width of the passage to be constant along the flow direction of fluid in the passage. 
 
     
     
       14. The flow measuring device according to  claim 1 , wherein the flow measuring element includes a flat-plate substrate parallel to the flow direction of fluid flowing in the passage, and a resistive element formed on a surface of the substrate. 
     
     
       15. A flow measuring device comprising:
 a housing defining a passage therein and including a passage narrowing part, which reduces a cross-sectional area of the passage, in a predetermined part of the passage; 
 a support having a platy shape and disposed along a flow direction of fluid flowing in the passage; and 
 a flow measurement element which is located inside the passage narrowing part and disposed on a surface of the support, the flow measurement element being configured to detect a flow rate of fluid flowing in the passage, wherein the passage narrowing part has an inner wall surface that gradually reduces a width of the passage in one of:
 a direction from a center side to an end side of the passage along a height direction of the passage, which is perpendicular to a direction of the width of the passage; and 
 a direction from one end side to the other end side of the passage along the height direction of the passage. 
 
 
     
     
       16. The flow measuring device according to  claim 15 , wherein:
 the passage narrowing part is formed such that a distance between the inner wall surface of the passage narrowing part adjacent to the flow measurement element and the flow measurement element along the direction of the width of the passage is smaller than a distance between a width narrowest part of the inner wall surface and the flow measurement element along the height direction of the passage; and 
 the width narrowest part has the narrowest width of the passage. 
 
     
     
       17. The flow measuring device according to  claim 16 , wherein the direction of the width of the passage is a thickness direction of the support having the platy shape. 
     
     
       18. The flow measuring device according to  claim 15 , wherein the height direction of the passage is a direction perpendicular to a thickness direction of the support having the platy shape. 
     
     
       19. The flow measuring device according to  claim 15 , wherein:
 the housing further includes a curved passage part, which defines the passage, on an upstream side or a downstream side of the passage narrowing part in the flow direction of fluid; 
 the curved passage part changes the flow direction of fluid perpendicularly; and 
 the passage narrowing part is formed such that:
 the passage narrowing part includes one inner wall surface and the other inner wall surface, which define the passage and are opposed to each other in the height direction of the passage, the other inner wall surface including a width narrowest part of the inner wall surface which has the narrowest width of the passage; 
 the one inner wall surface of the passage narrowing part is formed continuously with a radially outward part of an inner wall surface of the curved passage part; 
 the other inner wall surface of the passage narrowing part is formed continuously with a radially inward part of the inner wall surface of the curved passage part; and 
 a distance from the flow measurement element to the other inner wall surface of the passage narrowing part in the height direction of the passage is larger than a distance from the flow measurement element to the one inner wall surface of the passage narrowing part in the height direction of the passage. 
 
 
     
     
       20. The flow measuring device according to  claim 15 , wherein the passage narrowing part defines only an element disposing part of the passage in which the flow measurement element is disposed. 
     
     
       21. The flow measuring device according to  claim 15 , wherein the passage narrowing part defines a narrowing passage space having a triangular shape in cross-section on one side of the passage in the height direction of the passage, on which a width narrowest part of the inner wall surface having the narrowest width of the passage is located. 
     
     
       22. The flow measuring device according to  claim 15 , wherein the passage narrowing part defines a narrowing passage space having a trapezoidal shape in cross-section on both sides or one side of the passage in the height direction of the passage, a width narrowest part of the inner wall surface having the narrowest width of the passage being located on the one side of the passage. 
     
     
       23. The flow measuring device according to  claim 15 , wherein the passage narrowing part defines a narrowing passage space having a semicircular shape in cross-section on one side of the passage in the height direction of the passage, on which a width narrowest part of the inner wall surface having the narrowest width of the passage is located. 
     
     
       24. The flow measuring device according to  claim 15 , wherein the passage narrowing part is formed in a narrowing shape which is capable of aligning a flow of fluid flowing in the passage along a forward direction or a backward direction of the flow of fluid. 
     
     
       25. The flow measuring device according to  claim 15 , wherein the passage narrowing part is formed in a narrowing shape which is capable of aligning a flow of fluid flowing in the passage only along a forward direction of the flow of fluid. 
     
     
       26. The flow measuring device according to  claim 15 , wherein a ridge line of the inner wall surface of the passage narrowing part, which gradually reduces the width of the passage in the flow direction of fluid flowing in the passage, is formed in a curved or linear manner. 
     
     
       27. The flow measuring device according to  claim 15 , wherein:
 the inner wall surface of the passage narrowing part includes a straight line part near the flow measuring element; and 
 the straight line part maintains the width of the passage to be constant along the flow direction of fluid in the passage. 
 
     
     
       28. The flow measuring device according to  claim 15 , wherein the flow measuring element includes a flat-plate substrate parallel to the flow direction of fluid flowing in the passage, and a resistive element formed on a surface of the substrate.